Carla Del Ponte of the UN independent commission of inquiry on Syria confirmed on Sunday that testimonies collected from casualties and medical staff suggest that Syrian rebels have used the nerve agent sarin. See here.
Speaking in Italian to a Swiss-Italian TV network Del Ponte said:
"Our investigators have been in neighboring countries interviewing victims, doctors and field hospitals and, according to their report of last week which I have seen, there are strong, concrete suspicions but not yet incontrovertible proof of the use of sarin gas, from the way the victims were treated,"
"This was use on the part of the opposition, the rebels, not by the government authorities."